Yes it was just a crash not a location crash or something like that , after load all ok , and it was after 13 hours gameplay so it s not a big deal :) . Can i change my companion ? i have whale now .If i can how ? and the new companion is scaled to my level ?

No you can't change. Only once at the obelisk on Nordlig Island, that's all.
We actually did talk about if that should be a possibility, and ofc it would be nice, but we had already modded a lot and was close to releasing it - and the risk of making bugs with 7 different companions to choose between ...